Copyright © 2007 by Allyn and Bacon Theory of Evolution Darwin’s theory of evolution Cause of evolution Evidence of evolution theory Copyright © 2007 by Allyn and Bacon

Copyright © 2007 by Allyn and Bacon Darwin’s theory of evolution Question: origin of the organisms (plants, animals, bacteria, etc.) Evolution – descent with modification All species are descendants of ancestral species. Species changes. Charles Darwin (1809-1882) Copyright © 2007 by Allyn and Bacon

Copyright © 2007 by Allyn and Bacon Before Darwin, 18th century: Species were created by God Aristotle: species do not change Lamarck, 1809: species evolved Copyright © 2007 by Allyn and Bacon

Copyright © 2007 by Allyn and Bacon II. Cause of evolution Darwin: characteristics of animal and plants suit to environment - adaptation Beak Copyright © 2007 by Allyn and Bacon

Copyright © 2007 by Allyn and Bacon What causes the fit to environment? Lamarck: innate drive causes evolution Darwin: natural selection causes evolution Copyright © 2007 by Allyn and Bacon

1859: On the Origin of Species by Means of Natural Selection Observations: member difference, traits inherited, capable of over producing, competing for resources → individuals with traits favoring surviving and reproducing tend to leave more offspring → accumulation of favorable traits Adaptation is caused by selection

Copyright © 2007 by Allyn and Bacon Mantid Copyright © 2007 by Allyn and Bacon

Darwinian theory of evolution • Adaptation is caused by selection • New species develop if environment changes or organisms migrate to new environment • Adaptation to variety of environment → diversity of life • All species are from a common ancestor (unity of life) Note that • Individuals do not evolve, although they may change. • Acquired characteristics do not pass to offspring. • Natural selection amplifies/diminishes Inheritable traits.

III. Evidence of evolution theory 1. From direct observation Example: virus evolution % 100 Patient No. 1 Patient No. 2 75 50 Patient No. 3 Percent of HIV resistant to 3TC 25 2 4 6 8 10 12 Weeks

III. Evidence of evolution theory 2. From fossil record of changes over time 2 4 Bristolia insolens 6 4 8 3 Bristolia bristolensis 10 Depth (meters) 12 2 Bristolia harringtoni 14 16 18 1 Bristolia mohavensis San Bernardio, California Deposited 500 mya

Copyright © 2007 by Allyn and Bacon III. Evidence of evolution theory 2. From fossil record of changes over time and origin of new species (a) Pakicetus (terrestrial) (b) Rhodocetus (predominantly aquatic) Pelvis and hind limb Cetaceans (c) Dorudon (fully aquatic) Pelvis and hind limb (d) Balaena (recent whale ancestor) Copyright © 2007 by Allyn and Bacon

Copyright © 2007 by Allyn and Bacon Fossils provide evidence of evolution evidence for origin of new species evidence for chronological order Fossils show pattern of evolution Copyright © 2007 by Allyn and Bacon

III. Evidence of evolution theory 3. From homology of species: closely related species are similar in structure Humerus Radius Ulna Carpals Metacarpals Phalanges Human Cat Whale Bat Mammals evolve form a common ancestor - unity of life

Copyright © 2007 by Allyn and Bacon Anatomical and molecular homology show characteristics from deep ancestor shared by more species; Newly evolved characteristics are shared by small group of species. Copyright © 2007 by Allyn and Bacon

Copyright © 2007 by Allyn and Bacon Darwin: Species evolve Cause of evolution: natural selection with evidence direct observation fossil record homology Copyright © 2007 by Allyn and Bacon